Cross-Layer Coordinated Attacks on Cyber-Physical Systems: A LQG Game Framework with Controlled Observations

In this work, we establish a game-theoretic framework to study cross-layer coordinated attacks on cyber-physical systems (CPSs), where the attacker can simultaneously interfere the physical process and launch jamming attacks on the communication channels while the defender can dodge the jamming by dispensing with observations. The generic framework captures a wide variety of classic attack models on CPSs. Leveraging dynamic programming techniques, we fully characterize the Subgame Perfect Equilibrium (SPE) control strategies. We also specify the SPE observation and jamming strategies through dynamic programming equations and provide efficient computational methods to compute them. The results demonstrate that the physical and the cyber attacks are coordinated and depend on each other. On one hand, the control strategies are linear in the estimate, and the large estimate error caused by jamming will induce performance degradation. On the other hand, the capability in the physical layer has a significant impact on the observation and jamming strategies. Numerical examples illustrate the interesting interactions between the defender and the attacker through their observation and jamming strategies.